NewZed

There is an open channel between the windshield and the seal. Water can leak in from one place on the outside and a different place on the inside. Take it for a drive and see if water appears from nowhere and beads up on the inside of the lower corner of the seal when going around a corner. It can also leak through the door by the window and out between the door panel and the door. Run your fingers along the bottom of the door panel and check for wetness.

The drive shafts (Nissan calls them propeller shafts) are not the same lengths.

Just a thought, that might actually end up looking good. Cut the back off of a power steering pump and use the front as an idler. If the bearing and pulley are designed to take the load in the front it might even be sound, engineering-wise. Who knows, the back of the pump might even unbolt. Worst case, it provides the measurements for a fabbed-up idler pulley.

The other things connected to the power source can cause a voltage drop, but they won't cause zero voltage, like you reported the first time at the relay. That has to be a broken circuit. Not sure that the floor temp lamp or sensor would be involved in a zero reading. Your ignition switch tests don't say if you wiggled the wires or the connector, or the key. You said the problem was sporadic, sometimes there, sometimes not. Those are are the worst kinds of problems because you have to reproduce whatever causes the randomness. So you tested once but can't confirm much from that single test. I'm not sure how you're doing your measurements but you might start measuring with the connectors connected. Through the back of the plug. Then if you get a zero at the relay you can go back to the switch and see if it's zero, or the other side of the relay. And don't overlook the connectors themselves. I had a T plug at an alternator that looked fine but was not making electrical contact. I've also had my starter solenoid wire do that (almost bought a new starter but wiggled some wires first). When you get an odd result wiggle connectors while your meter is still connected. Tap the relay to see if the solenoid is stuck. Good luck, I've spent some time figuring things like this out and you have to think outside the box when you're getting weird results.

That sounds more like a bad ignition switch. It's not uncommon. Pin 71 gets its power directly from the switch. The pins in the electrical switch can get loose and have sporadic and weak contact. I had one, it was the Start pin, and it took me quite a while to figure out. You might remove the switch and check it, along with its wiring. The hardest part is removing one of the little screws that has a one-way head on it. Theft protection. Here is a link to a very nice color diagram. By a member there called Saridout. https://www.classiczcars.com/files/category/1-wiring-diagrams/ Here's a picture of the part, and its source link. It's behind the key. I had to restake the copper on the back to fix mine. https://zcardepot.com/all-products/electrical/ignition-switch

Your continuity tests might be confusing you. Better to measure resistance. And study the wiring diagram. If you look at the diagram I posted before you can see that Pin 34 is the ground circuit for the air regulator. And it's on the same circuit as the power supply for the pump. So if you measure continuity you are measuring back through the air regulator to ground. The pump ground wire is also connected to ground. So they are connected, circuit-wise, but only via a common ground and common power supply. The pump and air regulator are branches on the same circuit. If you measured resistance instead of continuity you'd probably get about 60 ohms,that's about what the air regulator heating element is. If you don't get 60 ohms then you might have a wire that has shorted directly to ground. It might also have destroyed your relay, or blown the fusible link. I would take a few more measurements, check your fusible links, and look for a wire with broken insulation.

Just went and pushed the rod back. I have lots of room, like you do. It's not at the end of the stroke though, and I have put many miles on it. Apparently, the factory stroke is 35 mm. 1.38".

Seems like that should work fine. A few mm there will probably be less than one mm at the TBO due to the ratio of the fork. It's not clear what problem that you're having. I watched your video and see that the piston is far down its stroke. But I don't know what the total stroke length is. Are you saying that when you press the pedal the fork doesn't move? If you were at the the end of the stroke the piston should pop out of the bore. My picture was taken with the pedal up. It was just me, a steel rule, and a camera. I'm going to go out and see if I can push the rod and piston back as far as you do in your video.

That will stop the pump from running once the engine starts. The engine will start then die, over and over, because there is no air keeping the AFM vane open. But the AFM switch is bypassed during Start, as shown in the wiring diagram. You need that hose to keep the engine running. But, since the hose is off it will be easy to stick a screwdriver in to keep the vane open. This should keep the pump running and allow the engine to stay running if you get it started. But it will only idle and maybe rise a few RPM before it leans out and starts backfiring or dies if you open the throttle. Unless you manipulate the AFM vane by hand at the same time to pretend it's measuring air flow.

Since yours is a 1976 model you can also prop open the AFM vane with the key on. Use something inside the AFM or take the black cover off of the side and move the damper weight. That will send power to the pump also.

If you measured 9 volts on one of the wires that is about right (actually it's low but it should still run your pump), with the voltage drop from the starter. You tested the pump and it works. That leaves the ground. Edit 2 - rethinking the 9 volts. That's pretty low even with the starter draw. Seems like the battery needs charging before further testing. It's not really clear why you were measuring continuity when all you needed was voltage and ground. If you disconnect the yellow wire at the starter solenoid you can get power to the pump without the engine turning over. The fuel pump will get power at Start but the starter won't. Makes it easier for testing. You can hear the fuel pump.

Here is a picture I took a while ago that might help you figure out where your problem is. It's the distance from the clutch fork to the head of one of the slave cylinder mounting bolts, on a properly working clutch system. It should tell you if you have the correct TOB sleeve inside. A short sleeve will measure more than 6 cm, a too-tall one will measure less. This is the starting point, and travel is fine.

Looks like Nissan used the R180 with the automatic transmission. 3N71B.

You're almost there. Your test of touching the wires together, which created a spark from the MSD box, shows that the last, missing, piece is the trigger from the pickup coil. You showed that you have a good pickup coil. The trigger voltage from the magnetic pickup is caused by a ferrous piece of metal passing by, the six bladed metal wheel next to the pickup coil. If you have a sensitive meter, or an analog meter, or an oscilloscope, you can see the voltage from the pickup coil when the distributor spins. Nissan even drew a picture of what the voltage looks like on an oscilloscope in the FSM, Engine Electrical chapter. Find a way to see if you're getting that voltage pulse when the engine spins. You haven't confirmed that the distributor shaft spins with the engine, for example. Things slip or break or get put together wrong. People have had the drive gear slip on the shaft. People forget to put the rotor under the cap. If you're testing for spark at the coil main wire take the distributor cap and rotor off and spin the distributor by hand. Or just watch it when you turn the engine over. Or lift the distributor up and spin it by hand with the key on. Lots of possibilities. Focus on the triggering system. One thing that might cause problems is if you have the wires connected backward. Maybe switch the red for the green. Usually it just causes timing problems but maybe the MSD is more sensitive and won't work with a backward waveform. There's also an air gap adjustment that needs to be right to generate voltage. Check that.

The test that you did here shows that your MSD wiring was correct. You're just not getting the voltage pulse from your distributor. Your MSD wiring looks right, it's your distributor's magnetic pickup signal that is not getting through. When you touch the green and violet wires together you create a voltage pulse that mimics what the distributor should do. Focus on the distributor.

And make sure the distributor is actually turning when the engine turns. You're at the "don't assume anything" point.

Measure resistance across the wires from the magnetic pickup in the distributor, with them disconnected. You might have the wrong ones connected or have a bad pickup. Should be about 720 ohms. You won't get repeated spark unless the trigger is triggering.

And, of course, there's always the possibility that you have a bad pickup coil in the distributor. Confirm proper resistance and air gap. But, you have two in there so you can always use the other.

Make sure that you're not losing power to your toggle switch when you turn the key to Start. The ignition system turns off all accessory power during Start to give maximum current to the coil. Start and Run are two different circuits.

There should be some troubleshooting steps here - https://static.summitracing.com/global/images/instructions/msd-6425.pdf

No, you want to connect the BW and BL wires from your ignition switch directly and together to the thin red wire. They provide the power to the MSD box with the key on and during Start. Power from the thick red wire passes through the box to the coil positive. The thin red wire turns the box on. If you're using a relay or switch for the thin red wire power, instead of the ignition switch, and it stays on while you're trying to to Start, then their might be something wrong with the box. It should spark if the thin red wire has power and all of the other wires are connected as shown.

I mis-wrote in my other post. MSD runs all power through the MSD box. There's an ignition wire, red, and a "heavy" power wire, also red. You only show one red wire, not real clear which one. By your drawing, you're missing one red wire. The BW and BL wires should both be connected to the thin red ignition wire, "original coil + wire". Yours would be the "magnetic pickup" scheme.

It's an old car that looks cool. Some people buy them just to have them in the garage, and never actually drive them. If you're looking for a daily driver, read through the many threads on this site to see what's involved in keeping them running. Looks like you should plan on having two cars for a while. Ideally, the other will be a truck so that you can haul parts, like engines and transmission. And expect to spend some money. Nickels and dimes will add up quickly. If it didn't need time and money he probably wouldn't be selling it. Lastly - do you like your neighbor now? Because you're going to find all of the "previous owner" stuff he did. Or he might be hanging out all the time pining over his old car.

Make sure that the original module is disconnected. And think of the MSD box as the make/break circuit on the grounded side, the negative side, of the coil. The coil gets power, the MSD box lets current flow, the MSD box cuts the current when the trigger wires tell it to...spark happens. Break it down in to the basics.

L = Blue